Joining method for coil ends of segment coils for stator and joining apparatus

ABSTRACT

A joining method for coil ends includes: pressing a pair of tapered portions such that a pair of first pressing jigs provided with a pair of detent portions is brought closer to the coil ends along an axial direction of the stator core, the pair of detent portions being fitted to the tapered portions; fixing axial positions of the pair of tapered portions such that the pair of detent portions is fitted to the pair of tapered portions so that the pair of tapered portions is sandwiched in a circumferential direction; fixing radial positions of the pair of tapered portions such that the pair of tapered portions is sandwiched by a pair of second pressing jigs so that the tapered portions of the pair of tapered portions make contact with each other; and welding a contacting portion where the tapered portions make contact with each other.

INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application No. 2015-212685 filed onOct. 29, 2015 including the specification, drawings and abstract isincorporated herein by reference in its entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to a joining method for coil ends ofsegment coils used for a stator, and a joining apparatus.

2. Description of Related Art

When a stator of a motor is manufactured, segment coils that form a coilby being joined together are used. A joining method for end parts ofsegment coils is described in Japanese Patent Application PublicationNo. 2006-304507 (JP 2006-304507 A). The segment coil is configured suchthat a distal end is formed in a tapered shape. The segment coils areassembled in order from an inner side to an outer side in a radialdirection of a stator core, and the segment coils of a pair of segmentcoils adjacent to each other in the radial direction are tilted inopposite directions to each other along a circumferential direction ofthe stator core. By this structure, a height of the coil ends isshortened. Then, a conductive adhesive is applied to to-be-joined partsof distal ends of a pair of segment coils as a joining target. Afterthat, a plurality of wedge-shaped plate bodies is inserted intorespective gaps of the distal ends of the pair of segment coils alongthe radial direction of the stator core, so that the to-be-joined partsare fixed at predetermined positions along the radial direction.Subsequently, a state where the plate bodies are pressurized at apredetermined pressure is maintained for a predetermined time, so as tocure the conductive adhesive, thereby joining segment coil ends to eachother.

SUMMARY

The joining method for the end parts of the segment coils, as describedin JP 2006-304507 A, uses a conductive adhesive, and does not describeanything about a joining method by welding. Further, in this method,distal ends of a pair of segment coils can be positioned along theradial direction of the stator core, but positioning along an axialdirection and a circumferential direction of the stator core is notdescribed. Accordingly, in a case where this method is to be used forwelding of distal ends of a pair of segment coils, such a problem occursthat the positioning along the axial direction and the circumferentialdirection of the stator core cannot be performed accurately.

The embodiments provide a coil end joining method and a joiningapparatus, each of which is able to accurately perform positioning ofcoil ends of segment coils in the manufacture of a stator core.

A first aspect relates to a joining method for coil ends of segmentcoils for a stator, and the joining method includes: assembling segmentcoils formed in a predetermined shape into slots of a stator coresequentially from an inner side toward an outer side in a radialdirection of the stator core; tilting coil ends of a pair of the segmentcoils adjacent to each other in the radial direction in the stator coreso that the coil ends are tilted toward mutually opposite directions ina circumferential direction of the stator core, the coil ends eachhaving a tapered portion having a distal end with a tapered shape andhaving a chamfer facing toward the stator core; pressing a pair of thetapered portions adjacent to each other in the radial direction in astate where the coil ends are tilted, such that a pair of first pressingjigs provided with a pair of detent portions is brought closer to thecoil ends along an axial direction of the stator core, the pair ofdetent portions being fitted to the pair of tapered portions; fixingaxial positions of the pair of the tapered portions such that a firstone of the pair of detent portions is fitted to the chamfer of a firstone of the pair of tapered portions and a second one of the pair ofdetent portions is fitted to the chamfer of a second one of the pair ofthe tapered portions; fixing radial positions of the pair of the taperedportions such that the pair of the tapered portions is sandwiched by apair of second pressing jigs from the inner side and the outer side inthe radial direction so that the tapered portions of the pair of taperedportions make contact with each other; and welding a contacting portionwhere the tapered portions of the pair of the tapered portions makecontact with each other.

According to the first aspect, when the tapered portions of the coilends in the stator core are pressed by the first pressing jigs, so thatthe pair of detent portions of the first pressing jigs is fitted to thepair of the tapered portions, it is possible to fix positions of thetapered portions along the axial direction of the stator core atpredetermined positions. Further, by sandwiching the pair of the taperedportions along the radial direction of the stator core by the pair ofsecond pressing jigs, it is possible to fix the radial positions of thetapered portions at predetermined positions.

The first aspect may further include fixing circumferential positions ofthe pair of the tapered portions such that, in a state where the firstone of the pair of detent portions is fitted to the chamfer of the firstone of the pair of the tapered portions and the second one of the pairof detent portions is fitted to the chamfer of the second one of thepair of the tapered portions, the pair of detent portions are moved soas to approach each other along the circumferential direction.

According to the above configuration, when the detent portions of thepair of detent portions are moved so as to approach each other along thecircumferential direction of the stator core so that the pair of thetapered portions are sandwiched along the circumferential direction ofthe stator core, it is possible to fix positions of the tapered portionsalong the circumferential direction of the stator core at predeterminedpositions. In this state, the tapered portions of the pair of thetapered portions are fixed to the predetermined positions in terms ofthe axial direction by the pair of detent portions, and also fixed alongthe radial direction of the stator core by the pair of second pressingjigs. That is, according to the above configuration, the taperedportions of the coil ends can be fixed at the predetermined positions interms of the axial direction, the radial direction, and thecircumferential direction of the stator core.

The detent portions may each have a fitting surface formed along thecircumferential direction and inclined to a direction approaching thestator core in the axial direction; and when the detent portions of thepair of detent portions are moved so as to approach each other along thecircumferential direction, the circumferential positions of the pair ofthe tapered portions may be fixed such that the respective chamfers ofthe pair of the tapered portions are fitted to the respective fittingsurfaces.

According to the above configuration, since the fitting surfaces areformed in the detent portions of the first pressing jigs, when the firstpressing jigs are moved in the circumferential direction of the statorcore, it is possible to surely fit the tapered portions of the coil endsto the detent portions. The method makes it possible to surely fix thetapered portions at the predetermined positions in terms of thecircumferential direction and the axial direction of the stator coresimultaneously.

Each of the first pressing jigs may have a penetration groove providedat a position corresponding to a position of the contacting portionalong the axial direction, the penetration groove being provided so asto weld the contacting portion, and laser welding may be performed onthe contacting portion from the axial direction through the penetrationgroove.

According to the above configuration, the contacting portion of the pairof the tapered portions fixed at the predetermined positions by thesecond pressing jigs and the first pressing jigs can be welded from theaxial direction of the stator core through the penetration groovesformed in the first pressing jigs. By applying a laser beam through thepenetration grooves, it is possible to weld the contacting portionwithout affecting the other part except for the pair of tapered portionsas a welding target.

A second aspect relates to a joining apparatus for coil ends of segmentcoils for a stator, and the joining apparatus includes: a pair of firstpressing jigs each having a flat surface, a detent portion projectingfrom the flat surface and having an inclined surface inclined relativeto the flat surface at less than 90°, and a penetration groovepenetrating the first pressing jigs in a generally perpendiculardirection with respect to the flat surface; and a pair of L-shapedsecond pressing jigs.

According to the embodiments, it is possible to accurately performpositioning of coil ends of segment coils at a time when the coil endsof the segment coils are joined in manufacture of a stator core.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, advantages, and technical and industrial significance ofexemplary embodiments will be described below with reference to theaccompanying drawings, in which like numerals denote like elements, andwherein:

FIG. 1 is a view illustrating a stator core as a manufacture object ofone embodiment;

FIG. 2 is a view illustrating to-be-joined parts of segment coils;

FIG. 3 is a view illustrating to-be-joined parts of segment coils;

FIG. 4 is a view illustrating a distal end of a coil end of a segmentcoil;

FIG. 5 is a view illustrating a modification of the distal end of thecoil end of the segment coil;

FIG. 6 is a sectional view illustrating a configuration of a coil endjoining apparatus according to one embodiment;

FIG. 7 is a sectional view illustrating the configuration of the coilend joining apparatus, when viewed from another direction;

FIG. 8 is a perspective view illustrating a detent portion of a firstpressing jig;

FIG. 9 is a view illustrating a joining method for coil ends by use ofthe coil end joining apparatus;

FIG. 10 is a view illustrating positioning of the coil end by the firstpressing jig;

FIG. 11 is a view illustrating positioning of the coil end by the firstpressing jig;

FIG. 12 is a view illustrating a deviation of bending of the coil end;

FIG. 13 is a view illustrating positioning of the coil end by the firstpressing jig;

FIG. 14 is a view illustrating a clamping device as a modification ofthe coil end joining apparatus;

FIG. 15 is a sectional view illustrating a configuration of the clampingdevice; and

FIG. 16 is a perspective view illustrating a detent portion of theclamping device.

DETAILED DESCRIPTION OF EMBODIMENTS

The following describes an embodiment of a coil end joining apparatusfor segment coils for a stator and a joining method thereof withreference to the drawings.

As illustrated in FIGS. 1 and 2, a stator 1 for a motor includes a toricstator core 2, and a plurality of segment coils 4 to form a coil 3inside the stator core 2. The stator core 2 is formed such that thintoric steel plates are laminated. Inside the stator core 2, a pluralityof segment coils 4 formed in a U-shape is arranged along acircumferential direction of the stator core 2. The plurality of segmentcoils 4 is laminated sequentially from an inner side toward an outerside along a radial direction of the stator core 2. The coil 3 is formedby the plurality of segment coils 4 assembled as such.

As illustrated in FIG. 3, a pair of coil ends 5 of a pair of segmentcoils 4 is adjacent to each other in the radial direction of the statorcore 2. The coil ends of the pair of coil ends 5 are tilted in oppositedirections to each other along the circumferential direction of thestator core 2. A distal end of coil end 5 has a tapered portion 6 formedin a tapered shape. The tapered portion 6 is formed to have such a shapethat the coil end 5 is cut parallel to the radial direction of thestator core 2 in a state where the coil end 5 is tilted. By thisstructure, a height of the coil end 5 along an axial direction of thestator core 2 is shortened. Distal ends of the pair of coil ends 5adjacent to each other are welded so as to be electrically connected.

As illustrated in FIG. 4, a chamfer 7 is formed in a distal end of thetapered portion 6 so that the distal end rises sharply in the axialdirection of the stator core 2. Due to the chamfer 7, an angle of thedistal end of the tapered portion 6 is formed to be larger than it wouldbe without the chamfer 7. An angle θ of the distal end of the taperedportion 6 is less than 90°. As illustrated in FIG. 5, the chamfer 7 maybe formed in an R-shape (a rounded shape) so as to project toward astator-core-2 side. For example, the tapered portion 6 is formed asfollows. A part of a belt-shaped lead wire extended in a linear shape isbent such that an axis of the lead wire deviates in parallel in alongitudinal direction of a section of the belt shape, so as to form abending portion. The bending portion is formed by molding the lead wirewith a die, for example. After that, the bending portion is pressed fromboth sides in a short direction of the section of the belt shape. Then,the bending portion is cut diagonally with respect to the axis of thelead wire from the longitudinal direction of the section of the beltshape of the bending portion, thereby forming the tapered portion 6having the chamfer 7.

Distal ends of a pair of tapered portions 6 adjacent to each other inthe radial direction of the stator core 2 are welded together. In thecircumferential direction of the stator core 2, welded portions (partswhere an insulation coating is removed) of respective pairs of taperedportions 6 are placed at intervals. By forming the distal ends of thetapered portions 6 in the aforementioned shape, it is possible toincrease an insulation distance between the welded portions adjacent toeach other in the circumferential direction of the stator core 2. Byincreasing the insulation distance, it is possible to reduce an eddycurrent loss of the segment coil 4. The following describes a coil endjoining apparatus 50 used for a pair of coil ends 5 adjacent to eachother in the radial direction and a joining method thereof.

As illustrated in FIGS. 6 to 8, the coil end joining apparatus 50includes: a pair of first pressing jigs 10, 10′ configured to positioncoil ends 5 in the axial direction and the circumferential direction ofthe stator core 2; and a pair of second pressing jigs 20, 20′ configuredto position the coil ends 5 in the radial direction of the stator core2.

A coil end 5′ is adjacent to the coil end 5 in the radial direction(Y-direction) of the stator core 2 so that a distal end of the coil end5 and a distal end of the coil end 5′ are directed toward oppositedirections. The first pressing jig 10 is fitted to a tapered portion 6of the coil end 5. The first pressing jig 10 is configured to positionthe tapered portion 6 along the axial direction (Z-direction) and thecircumferential direction (X-direction) of the stator core 2. A flatportion 11 that is flat along the X-direction so as to press the taperedportion 6 is formed in a bottom of the first pressing jig 10.

A detent portion 12 formed so as to project downward (−Z-direction) isformed in the flat portion 11. A fitting surface 14 inclined toward amoving direction (−X-direction) where the detent portion 12 moves isformed in the detent portion 12. The fitting surface 14 is formed alongthe circumferential direction (X-direction) and is inclined in adirection approaching the stator core 2 in the axial direction(Z-direction). The detent portion 12 is formed so as to enter a space Sformed between the chamfer 7 of the coil end 5 and its adjacent coil end5 in the X-direction so as to prevent interference with the adjacentcoil end 5 in the X-direction. The tapered portion 6 is fitted to thefirst pressing jig 10 due to the flat portion 11 and the detent portion12.

The first pressing jig 10′ configured to press the coil end 5′ isadjacent to the first pressing jig 10 in a −Y-direction. The coil end 5′and the first pressing jig 10′ have the same configurations and shapesas the coil end 5 and the first pressing jig 10, respectively, and areplaced in rotation symmetry to a Z-axis. Accordingly, in the followingdescription, the coil end 5′ and the first pressing jig 10′ have thesame configurations described above. A penetration groove 13 penetratingalong the Z-axis direction is formed in the first pressing jig 10. Thepenetration groove 13 is provided in the first pressing jig 10 in apenetrating manner at a position corresponding to a position of thetapered portion 6 along the Z-axis direction. One through-hole to weldthe coil ends 5 is formed by the penetration groove 13 and a penetrationgroove 13′.

As illustrated in FIG. 9, the first pressing jig 10 moves so as toapproach the coil end 5 in the −Z-direction along the Z-axis, and stopsat a reference position P while applying a force in the −Z-direction. Atthis time, the detent portion 12 enters the space S so as not to makecontact with the chamfer 7. By this structure, an upper end of thetapered portion 6 of the coil end 5 abuts with the flat portion 11, anda force is applied to the coil end 5 in the −Z-direction by the firstpressing jig 10. At this time, the upper end of the tapered portion 6 isplaced at the reference position P, and a position of the taperedportion 6 in the Z-axis direction is fixed.

Similarly, a position of a tapered portion 6′ of the coil end 5′ in theZ-axis direction is also fixed by the first pressing jig 10′. That is, apair of tapered portions 6, 6′ is pressed in the axial direction of thestator core 2 by the pair of first pressing jigs 10, 10′, so that thepositions of the pair of tapered portions 6, 6′ in the axial directionof the stator core 2 are fixed.

After that, the first pressing jig 10 moves in the −X-direction, and thedetent portion 12 abuts with the chamfer 7. By this process, the taperedportion 6 is fitted to the first pressing jig 10, so that a position ofthe tapered portion 6 in the X-axis direction is fixed. Similarly, aposition of the tapered portion 6′ of the coil end 5′ in the X-axisdirection is also fixed by the first pressing jig 10′. That is, in astate where the detent portion 12 is fitted to the chamfer 7 of thetapered portion 6 and the detent portion 12′ is fitted to the chamfer 7′of the tapered portion 6′, the detent portions of the pair of detentportions 12, 12′ are moved so as to approach each other along thecircumferential direction, so that the positions of the pair of taperedportions 6, 6′ in the circumferential direction are fixed.

At this time, when the detent portions of the pair of detent portions12, 12′ are moved so as to approach each other along the circumferentialdirection, respective chamfers 7, 7′ of the pair of tapered portions 6,6′ are fitted to respective fitting surfaces 14, 14′, so that thepositions of the pair of tapered portions 6, 6′ in the circumferentialdirection are fixed. Hereby, the pair of tapered portions 6, 6′ issandwiched by the pair of first pressing jigs 10, 10′ in thecircumferential direction of the stator core 2 so as to be fittedthereto, and thus, the positions of the pair of tapered portions 6, 6′in the circumferential direction of the stator core 2 are fixed.

As illustrated in FIGS. 10 to 13, the position of the segment coil 4variously changes. When a bending angle of the segment coil 4 is small,the coil end 5 projects upward (Z-axis direction) relative to thereference position P (see FIG. 10). In this case, when the firstpressing jig 10 moves down along the Z-axis so as to press the taperedportion 6 downward, the tapered portion 6 is placed at the referenceposition P. In the meantime, when the bending angle of the segment coil4 is large, the coil end 5 is positioned downward (−Z-axis direction)relative to the reference position P (see FIG. 11). rating generally thefirst pressing jigs in a generally perpendicular direction with respectto portion 6 upward by the detent portion 12. That is, the chamfer 7 ofthe tapered portion 6 slides up over the fitting surface 14 of thedetent portion 12 so that the detent portion 12 is fitted to the taperedportion 6. By this process, the tapered portion 6 is placed at thereference position P.

Further, when a curve R of the segment coil 4 is too large (see FIG.12), the position of the coil end 5 is placed to deviate in the X-axisdirection. In this case, the first pressing jig 10 moves along theX-axis so as to move the tapered portion 6 in the −X-direction by thedetent portion 12. By this process, a force to compress the taperedportion 6 in the axial direction of the segment coil 4 is applied due tothe detent portion 12 and the flat portion 11, so that the curve R isreduced and the tapered portion 6 is placed at a correct position (seeFIG. 13).

Next will be described positioning of the coil end 5 with respect to theradial direction of the stator core 2. Both sides of the pair of coilends 5, 5′ are sandwiched by the pair of second pressing jigs 20, 20′along the Y-axis direction (see FIG. 7). Distal ends of the pair ofsecond pressing jigs 20, 20′ are provided with protruding portions 22,22′ configured to sandwich the pair of tapered portions 6, 6′ from bothsides. The protruding portions 22, 22′ are formed so as to project inthe −Z-direction to enter spaces Q, Q′ between a plurality of pairs oftapered portions 6, 6′ adjacent to each other in the radial direction ofthe stator core 2. That is, the pair of coil ends 5, 5′ is sandwiched bythe pair of second pressing jigs 20, 20′ from an inner side and an outerside in the radial direction of the stator core 2. By this process, amovement of the pair of coil ends 5, 5′ in the Y-axis direction isrestricted. The positions of the pair of tapered portions 6 in theradial direction of the stator core 2 are fixed to their correctpositions.

Due to the pair of first pressing jigs 10, 10′ and the pair of secondpressing jigs 20, 20′, the pair of tapered portions 6, 6′ is fixed inthree axial directions of the axial direction, the circumferentialdirection, and the radial direction of the stator core 2, and are placedat their correct positions. At this time, the pair of tapered portions6, 6′ make contact with each other, so that a contacting portion B isformed. The contacting portion B can be observed through the penetrationgrooves 13, 13′ from an upper side in the Z-axis. After that, thecontacting portion B is welded with a laser beam 31 by a laser welder 30from the upper side in the Z-axis direction through the penetrationgrooves 13, 13′. When the laser beam is applied through the penetrationgrooves 13, 13′, it is possible to weld the contacting portion B withoutaffecting other parts except for the contacting portion B as a weldingtarget.

As described above, according to the joining method for the coil ends 5of the segment coils 4, in a case where the coil end 5 has the taperedportion 6 formed in a tapered shape, it is possible to accuratelyposition the pair of tapered portions 6, 6′ at their correct positions.Further, it is possible to perform laser beam welding on the pair oftapered portions 6, 6′ through the penetration grooves 13, 13′ providedin the pair of first pressing jigs 10, 10′. With the use of thepenetration grooves 13, 13′, it is possible to prevent other partsexcept for the welding target from being affected. According to thejoining method for the coil ends 5, it is possible to reduce an overalllength of the segment coils 4, thereby making it possible to downsize amotor to be manufactured from the stator coil. Further, by reducing theoverall length of the segment coils 4, it is possible to reduce amanufacturing cost of the motor.

The above embodiment is not intended to be limiting, and variousmodifications can be made to it.

As illustrated in FIG. 14, a clamping device 40 may be provided suchthat a plurality of pairs of first pressing jigs 10, 10′ and a pluralityof pairs of second pressing jigs 20, 20′ are arranged so as to extend inthe circumferential direction of the stator core 2. In the followingdescription, the same configuration as the one described in the abovedescription uses the same name and reference sign and a similarconfiguration to the above uses the same name, so redundant descriptionsthereof are omitted.

The clamping device 40 includes a toric inner-side clamp 41, a toricouter-side clamp 42 placed on an outer peripheral side relative to theinner-side clamp 41, and a plurality of second pressing jigs 43 placedradially on the outer peripheral side relative to the outer-side clamp42. A plurality of penetration grooves 41 a, 42 a is formed in theinner-side clamp 41 and the outer-side clamp 42, respectively. Athrough-hole H is formed by a pair of penetration grooves 41 a, 42 a.The inner-side clamp 41 and the outer-side clamp 42 are rotatablerelative to each other concentrically.

As illustrated in FIG. 15, the second pressing jig 43 is placed on aside surface of the outer-side clamp 42 so as to be slidable in theY-axis direction. A protruding portion 41 b opposed to the secondpressing jig 43 is provided on a bottom face of the inner-side clamp 41.A pair of tapered portions 6, 6′ is sandwiched by the second pressingjig 43 and the protruding portion 41 b along the Y-axis direction.

As illustrated in FIG. 16, the pair of tapered portions 6, 6′ issandwiched in the circumferential direction of the stator core 2 by adetent portion 41 c formed on the bottom face of the inner-side clamp 41and a detent portion 42 c formed on a bottom face of the outer-sideclamp 42. A plurality of pairs of tapered portions 6, 6′ extended in thecircumferential direction of the stator core 2 is positioned in thecircumferential direction of the stator core 2 by the relative rotationbetween the inner-side clamp 41 and the outer-side clamp 42. Theplurality of pairs of tapered portions 6, 6′ is positioned in the axialdirection of the stator core 2 by the inner-side clamp 41 and theouter-side clamp 42. After that, contacting portions B of the pluralityof pairs of tapered portions 6, 6′ are subjected to laser weldingthrough the through-holes H.

Further another plurality of pairs of tapered portions 6, 6′ extended inthe circumferential direction of the stator core 2 are positioned by aclamping device 40 having a different outside diameter, and thensubjected to laser welding.

What is claimed is:
 1. A joining method for coil ends of segment coilsfor a stator, the joining method comprising: assembling segment coilsformed in a predetermined shape into slots of a stator core sequentiallyfrom an inner side toward an outer side in a radial direction of thestator core; tilting coil ends of a pair of the segment coils adjacentto each other in the radial direction in the stator core so that thecoil ends are tilted toward mutually opposite directions in acircumferential direction of the stator core, the coil ends each havinga tapered portion having a distal end with a tapered shape and having achamfer facing toward the stator core; pressing a pair of the taperedportions adjacent to each other in the radial direction in a state wherethe coil ends are tilted, such that a pair of first pressing jigsprovided with a pair of detent portions is brought closer to the coilends along an axial direction of the stator core, the pair of detentportions being fitted to the pair of tapered portions; fixing axialpositions of the pair of the tapered portions such that a first one ofthe pair of detent portions is fitted to the chamfer of a first one ofthe pair of the tapered portions and a second one of the pair of detentportions is fitted to the chamfer of a second one of the pair of thetapered portions; fixing radial positions of the pair of the taperedportions such that the pair of the tapered portions is sandwiched by apair of second pressing jigs from the inner side and the outer side inthe radial direction so that the pair of tapered portions make contactwith each other; and welding a contacting portion where the taperedportions of the pair of the tapered portions make contact with eachother.
 2. The joining method according to claim 1, further comprising:fixing circumferential positions of the pair of the tapered portionssuch that, in a state where the first one of the pair of detent portionsis fitted to the chamfer of the first one of the pair of the taperedportions and the second one of the pair of detent portions is fitted tothe chamfer of the second one of the pair of the tapered portions, thepair of detent portions are moved so as to approach each other along thecircumferential direction.
 3. The joining method according to claim 1,wherein: the detent portions each have a fitting surface formed alongthe circumferential direction and inclined to a direction approachingthe stator core in the axial direction; and when the detent portions ofthe pair of detent portions are moved so as to approach each other alongthe circumferential direction, the circumferential positions of the pairof the tapered portions are fixed such that the respective chamfers ofthe pair of the tapered portions are fitted to the respective fittingsurfaces.
 4. The joining method according to claim 1, wherein: each ofthe first pressing jigs has a penetration groove that penetrates thefirst pressing jigs along the axial direction at a positioncorresponding to a position of the contacting portion along the axialdirection; and laser welding is performed on the contacting portionthrough the penetration groove.
 5. A joining apparatus for coil ends ofsegment coils for a stator, the joining apparatus comprising: a pair offirst pressing jigs each having a flat surface, a detent portionprojecting from the flat surface and having an inclined surface inclinedrelative to the flat surface at less than 90°, and a penetration groovepenetrating the first pressing jigs in a generally perpendiculardirection with respect to the flat surface; and a pair of L-shapedsecond pressing jigs.